Process for the manufacture of substances having porous structure



United States Patent Claims. (Cl. 106-122) The present application is acontinuation-in-part application of application Serial No. 846,261 filedOctober 14, 1959, now abandoned. v

Organic hydrophobing agents which can be applied in the form ofsolutions inorganic solvents have attained steadily increasingimportance in industry because they permit re-impart-ing water-repellingproperties to clothing made of leather, or particularly of textilematerial, which has been cleaned with organic solvents. The extensiveapplication of this hydrophobing method is due to the variousdisadvantages involved in the formerly used aqueous re-hydrophobing.Thus, for example, the water used in aqueous re-hydrophobing causes theclothing to swell, and the dragging or shrinking of the materials causedeformations which can be repaired only, if at all, by ironing. Further,the time necessary for the aqueous hydrophobing baths, which in mostcases are applied in the form of emulsions, to penetrate into theclothing is much longer than that of solutions of the agents in organicsolvents; the same is true of the drying time after impregnation. 'Inaddition thereto it is only possible to achieve the same hydrophobingeffect on goods made water-repellent in an aqueous medium byafter-heating them to an elevated temperature; in consequence thereof,the goods made Water-repellent in such a manner are much more liable tocreasing. Furthermore, the handle of goods made water-repellent inorganic solvents is softer and more agreeable, since the protectivecolloids, for example such as glue, the use of which is necessary whenapplying aqueous hydrophobing agents, cause a hard handle (cf. Monheim,Farber-Zeitung Der F'airber und Chemischreiniger, volume 6, No. 11, Nov.1953, pages 1-3).

As solid, organic hydrophobing agents that are suitable for thesepurposes, there are now also used particularly the alcoholates ofpolyvalent metals, such,'for example, as aluminum, zirconium andtitanium. In most cases they are applied in a form which can be more orless reacted in a known way with about 0.1 to 3 moles of monobasicorganic substances of acid nature, such, for example, as carboxylicacids or their anhydrides, like formic or'acetic or propionic acid,caprylic acid, lauric acid, myristic acid, aromatic monocarboxylicacids, monosulfinic acids, monosulfonic acids, phosphonic acids, ororganic monosulfuric acid or phosphoric acid esters, particularly fattyacids of high molecular weight, such for example, as stearic or oleic orpalmitic acid, as well as metal-alcoholates branched by metal-oxygenlinkages.

In this regard are mentioned as examples the semior mono-stearates ofaluminum ethanolate or isopropylate or sec. butanolate or amylate orhexanolate or '2-ethyl hexanolate, or the corresponding Ti or Zrcompounds, which, in addition, may be partially reacted in known waywith about 0.1 to 3 mols of keto-enol compounds, such, for example, asaceto-acetic ester, like methyl, ethyl, isopropyl, butyl, amyl esters,or aliphatic ,B-diketones like acetyl-acetone, 2,4-diketo-hexane or3,5-diketo-octane, or malonic acid dimethyl ester or diethyl ester ordibutyl ester, to prevent early decomposition by humidity, or withneutral salts of the metals mentioned above with lower or highercarboxylic acids, for example, aluminum-diacetate-monostearate. Suchorganic hydrophobing agents are described, for example, in German Patent968,936, in German patent specifications 1,004,585, 1,025,824, and1,039,991, in US. Patents 2,838,422, 2,877,248, and 2,801,190, inItalian Patent 555,656, and in published German patent application No.18,338 IVc/ 8k.

Lesser water-repelling effects are produced by the known, basic,hydroxy-group-containing salts of polyvalent metals, for example basicaluminum-distearate, by fatty acid anhydrides, or fatty acid methylolamides, or N,N'-ethy1ene ureas, for example, hexadecyl-N-ethylene urea,or copolymers of maleic acid, or their esters with vinyl ethers ofhigher molecular weight, such as octadecylvinyl ether or derivatives ofpolymethylolaminoor polyaZirino-triazines containing aliphatic radicalsof higher molecular weight, for example, the lauric or stearic acidradical.

These organic hydrophobing'agents are used together with about 0.5-3parts by weight of paraffin which mostly has an average solidificationpoint of about 40l00 C., more particularly 60 C., but rarely withparafiin slack waxes or waxes, because the hydrophobing is considerablyimproved despite the fact that the parafiins alone have only a poorhydrophobing effect. Even oily, organic hydrophobing agents, forexample, known aliphatic isocyanates of higher molecular weight, such,for example, as ocetadecyl isocyanate, namely in a form solidified byparaffin, enter into consideration.

In general, these mixtures of hydrophobing agents have a*solid, or moreseldom a semisolid consistency. The massive, compact form isinappropriate for easy manipulation by the consumer when measuring smallamounts, since at ordinary temperature it can only be comminuted withthe aid of crushing tools; a solvent-free product in shred-likeorpowder-like form, on the other hand, is liable 'to cake togetherparticularly at summer temperatures. For these reasons, these mixturesof hydrophobing agents are marketed in admixture with about equal partsof the solvents used for the impregnation bath, in particular Whitespirit and perchlorethylene, that is in the form of a body which atordinary temperature is grease-like and cuttable. These preparations,however, have many disadvantages in practice. Thus, evaporation of thesolvent 7 often causes changes of the concentration of the solvent aswell as incrustations at the walls of the containers. Already in mildheat the product looses its homogeneity because of partial melting ofthe solid components. Furthermore, the solvents used also involve manyrisks, for example, of intoxication and flammability. Moreover, thepreparations that contain solvents have a higher transport weight thanthe solvent-free preparation. Weighing and measuring at ordinarytemperature can be carried out incorrectly only. At lower temperatures,it is necessary to melt the products before measuring, which on the onehand, consumes time, and on the other hand, leads to incorrect doseswhen the products are inhomogenous due to incomplete melting. Storage ofthe products is often complicated by the fact that each solvent requiresa specific greasy consistency. Finally, the greasy consistency alsocauses inconvenient, additional work since any spilled product cannot beswept up, but must be wiped away.

Now, we "have found that the aforesaid hydrophobing agents for use inorganic solvents can be given a new, solid, porous consistency, whichrenders them easily manip-ulable and avoids the disadvantages described,by introducing an inert gas or air into the said solid organichydrophobing agents, in a fused state .at a temperature above thesolidification point, and cooling the products in this foamy state,having a specific gravity of about to about 33% of the gravity of thefused state of the hydrophobing agent, until solidification occurs.These organic hydrophobing agents agents contain paraifin and aresolidified by addition of paraflin; they do not contain water,emulsifiers, foam stabilizers or Waxes; they contain the aforesaidaluminum, zirconium or titanium compounds and. are soluble in low ormedium-boiling aliphatic or chlorinated aliphatic hydrocarbons, oraromatic or chlorinated aromatic hydrocarbons. The aliphatic or aromaticor chlorinated hydrocarbons mentioned comprise, for example, benzine,white spirit, carbon tetrachloride, trichlorethylene, perchlorethylene,toluene, chlorobenzene or mixtures of these solvents.

If such a foamy-porous melt is emptied into buckets, casks or linedbags, the porous mass, after solidification, can easily be cut out byhand at ordinary temperature without using crushing tools as isnecessary with massive products and in the same manner as thesolventcontaining grease-like mixture; when very cold, the productsaccording to this inventon can be cut even more easily than can agrease, since the solvent-containing grease solidifies to a compact,wax-like mass. Weighing manipulations can be carried out--even inmoderate heat, cleanly and conveniently. The transport weight of thesehydrophobing agents is low due to the economy of weight attained by theomission of the solvent. Neither inflammable nor toxic vapors areformed, so that protective measures can be dispensed with.

Storage is simplified since the products according to this invention canbe used generally in all the solvents used in practice. If the meltaccording to this invention is allowed to solidify to form sheets, thelatter can be cut up more easily than massive sheets. Semi-solid,organic, hydrophobing agents in porous form have a better coherence andincline less to stringing and running, which improves their homogeneity,in particular at mild heat during transport.

Although it is valuable with regard to application that solvents areabsent, the process of the present invention can be carried out also inthe presence of small additions of organic solvents of about 0.0110%,like lower aliphatic alcohols, hydrocarbons like white spirit ortoluene, chlorinated hydrocarbons like perchlor-ethylene or mixtures ofthese solvents; in this case, the solidified, porous consistency of theproduct offers the advantage of a smaller amount of solvent difllusingthrough the surface, thus reducing the risks of ignition andintoxication.

The porous form according to the present invention offers unexpectedadvantages on subsequent dissolving in solvents, since We have foundthat the solidified, porous, hydrophobing agents dissolve at ordinarytemperature faster than the same quantity by weight of the massive andthe corresponding amount of the grease-like forms. The solidified porestructure according to this invention, which at a temperature just belowthe melting point still has improved the coherence and homogeneity, ismuch more quickly decomposed by the action of organic solvents than thewax-like greasy structure of the hitherto used solvent mixtures.

The incorporation of the gas pores, the quantity of which may be soadjusted as to lower the specific gravity of the products to about 95 to33 percent, preferably to 80 to 50 percent of the specific gravity ofthe hydrophobing agent in the fused state, and the size of which mayrange between 0.1 mm. and 5 mm., preferably /2 mm. and 1 mm., can beeffected in various ways. The organic hydrophobing agent, as mixturesthereof with parafiin, may first be melted. Inert gases, for exampleair, carbon dioxide, or nitrogen may then be introduced into the melt,through frits forexample, particularly when the melt is at a temperaturenear the dropping point. The gases may be introduced under pressure, andthe melt is preferably stirred, for example with Archimedean stirringdevice such as crutchers. Alternatively, gas-forming materials such asinorganic or organic substances, soluble in organic solvents andyielding carbon dioxide or nitrogen, may be added to the melt. The hot,foamy, but still pourable or movable melt is then, if necessaryunderreduced pressure, caused to solidify to an appropriate solid formin, for example, buckets, bags or casks. These solidified .porous massescan be more easily cut out from the containers with scoops, orcomminuted than can a massive solidified product.

In order to facilitate easier dosing on dissolving, it is advantageousto make up the hydrophobing agent in the form of scored sheets of aweight commonly used com mercially. For transport, such sheets can bepacked, for example, in, foils used commercially for such purposes andmade of, for example, regenerated cellulose, and they can be enclosed inbags or rectangular containers made of paperboard or wood, for example,cardboard boxes or cases, without sweating through occurring even justbelow the melting point.

The foamy, if desired more or less solid melt may also be processed intoother forms. For example, it can be extruded and cut into chips orflakes or into bodies of cylindrical or angular section or in :balls.The foamy melt may also be converted into chips or scales or slack. Forthis purpose it is continuously supplied in a thin layer to a rotatingroll, which is cooled from the interior and, after solidification, it iscontinuously scraped oif from the cooling roll by means of a knife.Solid to hard parafiins and a low degree of foaming are suitabletherefor, the density of the melt being reduced by about one tenth toone third. The scales are prepared in a manner analogous to thepreparation of NaOH scales described by Kirk-Othmer in Encyclopedia ofChemical Technology, volume I, page 425, paragraph 3.

Even semi-solid mixtures of the hydrophobing agents that contain, ifdesired, small additions of solvents, can be provided with gas bubbles,for example, in molten state, and then cooled in, for example, bucketsor cups, to solidify partially into a foamy-creamy form. Thisconsistency also has the advantage that it can be cut out moreeasily'and more cleanly from the containers, for example, buckets orcups than the pore-free mass, and that it dissolves faster in organicsolvents.

It has already been proposed to prepare opaque parafiin for themanufacture of waxworks, in particular candles, by stirring finelydistributed air bubbles into the melt without having to add cloudingagents, and, since these parafiin melts easily give off these gasbubbles, it has also already been proposed to add to these melts foamstabilizers such as alkali salts of anion-active detergents, orrn'icrocrystalline Waxes (US. Patent 2,185,046, US. Patent 2,583,938;Seifen-Ole-Fette-Wachse (1957), page 749). There could, however, not bedrawn any conclusions therefrom on the behaviour of water-free andemulsifier-free paraffin-containing melts of strongly hydrophobicorganic hydrophobing agents in the absence of foam stabilizers, becausethese hydrophobing agents are not waxes, neither chemically norphysically, e.g. inter alia they are not polishable and form strings attemperatures above the melting point. On the contrary, it had to befeared that these products would considerably more reluctantlyincorporate gas bubbles than the melts of the paraffin which is onlyslightly hydrophobic. These publications do not disclose any statementson the behaviour of'the products concerned towards organic solvents.

The following examples serve to illustrate the invention but they arenot intended to limit it thereto.

Example 1 Into 10 kg. of a molten mixture (Ubbelohde-flowing point 56C., dropping point 57 C.) consisting of 7 kg. of parafiin (softeningpoint 55 C.), 2.5 kg. of the monostear a-te or mono-oleate of aluminumethanolate and con tact paraflin (softening point C.), there isintroduced air at about 53 C. by means of a frit and while stirring, forso long a period until a solidified sample of the creamy melt shows aspecific gravity of 0.60 (instead of originally 0.87). The foamy melt isthen poured to form rectangular sheets weighing 1 kg., having a size of20 X 2.8 cm. and containing in regular distribution grooves for easierpartition. Rectangular portions thereof having 20 X 6 x 2.8 cm. in sizeand 200 g. in weight, dissolve in 5 liters of perchlorethylene, whilestirring, and at 30 C. within about 30 minutes, whereas massive portionshaving the same weight and a size of 20 x 4 X 2.8 cm., of the same butpore-free mixture are dissolved under otherwise equal conditions afterabout 200-220 minutes.

At about 20 C., the porous portions are dissolved after about 50minutes, whereas the massive portions are dissolved after about 300minutes; rectangular, solventcontaining, grease-like portions having asize of 20 X 6.3 X 2.8 cm., 400 g. in weight and containing 50 percentby weight of perchlorethylene, require about 100 minutes to dissolve.

If instead of the monostearate of aluminum-ethanolate the same amount ofaluminum-diacetate-monopalmitate or monolauric titaniumorzirc'onium-butanolate or octadecyl-isocyanate or the reaction product of1 mol of stearic acid and pentamethylol-melamine-pentarnethyl ether isused, similar results are obtained.

If one of the above described foamy melts is allowed to solidify inbuckets having a capacity of liters, the porous filling mass can be cutout at about 30 C. with a scoop and dissolved in white spirit or carbontetra chloride equally well as a similar pasty, pore-free mass preparedwith a part by weight of perchlorethylene.

If, however, a pore-free melt of the same mixture of substances isallowed to solidify in similar buckets, the mass can be comrninuted withcrushing tools only or must be melted down, which is very time consumingdue to the low thermal conductivity of the mixture. During the meltingof grease-like, solvent-containing mixtures, a large part of solventevaporates whereby disadvantageous changes in concentrations are caused,and odors or flammable vapors may be generated.

Example 2 Into the melt of 10 kg. of paraffin and 10 kg. of distearateof aluminum sec.-butanolate prepared according to German Patent 569,946,nitrogen is introduced at 90 C. and with intensive stirring, by means ofa frit until the volume has increased by A and the specific gravity hasdecreased to 90% of the initial melt. The foamy melt is then emptied onplates or into buckets provided with bars. The resulting porous form ismore easily dissolved than the corresponding pore-free form.

The foamy melt of Examples 1 and 2 may be continuously supplied in athin layer to a rotating roll which is cooled from the interior. Fromthis roll, the solidified mass can be scraped off whereby it falls downin the form of scales and chips which are more rapidly soluble inperchlor-ethylene or white spirit at normal temperature than scales orchips free from pores.

Example 3 100 kg. of a mixture (Ubbelohde flowing point 55 C., droppingpoint 56 C.), that has been melted at 60 C., of 70 kg. of paraffin(softening point 54 C.) and 25 kg. of stearic aluminum-isopropanolateprepared from 0.8 mol of stearic acid (softening point 65 C.), 0.4 molof aoeto-acetic acid ester and 1 mol of aluminum-isopropanolate, arestirred by means of a high speed anchorshaped stirrer (150 revolutionsper minute) which revolves close by the wall of a 250 l. stirringvessel. Water at 45 C. is circulated through a cooling mantle. Uponcooling of the melt from 60 C. to 54 C., while stirring continuously,only a few foam bubbles appear at the surface of the melt. When thetemperature of the melt is then allowed to fall within one hour to 52C., fine porous foam distributes uniformly in the melt, the volume ofwhich rises by about /3. Simultaneously small sized solidified portionsdistribute uniformly in the melt. A sample of the foamy, but stillmostly oily mass shows a specific gravity of 0.53, whereas a massive,solidified sample taken at the beginning shows a specific gravity of0.88. By introducing nitrogen, at about 5l-52 C. and while continuouslystirring, into the melt by means of a tube provided with frit-likeopenings, the volume can be conveniently increased. The introduction ofgas and stirring are discontinued when a sample of the foamy mass showsa specific gravity of 0.40.

The still thickly liquid foam is then discharged, while continuingstirring and at temperatures closely below the solidification point,into suitable forms, for example, in boxes that are higher than they arebroad, such as corrugated paperboard folding boxes. The size of theseboxes is advantageously selected so that the thickness of the sheetsobtained permits cutting them by hand with a knife. Boxes having, forexample, the size of 400 X 500 X 125 mm. are suitable. Such boxes of 25liters capacity give sheets weighing 10 kg. To permit easy partition ofthe sheets, without weighing, into portions each weighing 2 kg,horizontal divider pads can be inserted in the boxes, which pads areelevated toward the interior, for example, 4 pads in intervals of 100mm. If the sheets are to be shipped at elevated temperatures a suitablebag, for example made of polyethylene, .acetyl cellulose or celluloseglass foil, can be inserted into the boxes before filling.

Chips or scales of about 0.1-5 g. can be planed off with a planingmachine from the solidified sheets of the porous hydrophobing agents ofExamples 1-3. These porous chips or scales are more rapidly soluble thanchips or scales free from pores planed off from passive sheets of thehydrophobing agents.

We claim:

1. The method of making .a shaped solid-foam 'body adaptable to solutionin organic solvents to form textile hydrophobing solutions, which methodcomprises forming .a melt of an anhydrous hydrophobing agent consistingessentially of (a) 0.5 to 3 parts by weight of paraflin having asolidification point of from 40 to 100 C., (b) one part by weight of amember selected from the group consisting of (1) aluminum, ziconium, andtitanium alcoholates of aliphatic alcohols having 2 to 8 carbon atoms,(2) said alcoholates reacted with from 0.1 to 3 mols of a monocarboxylicaliphatic acid per mol of alcoholate, said acid having 1 to 18 carbonatoms, and (3) the compounds of groups 1) and (2) reacted with from 0.1to 3 mols of an aliphatic keto-enol per mol of compound, and (c) 0.01 to10 percent, of the combined weight of (a) and (b), of an organic solventselected from the group consisting of a lower aliphatic alcohol,toluene, perchloroethylene, white spirits, and mixtures thereof,dispersing an inert gas in said melt in amounts sufficient to produce afluid foamed melt having a specific gravity about to 33% that of thespecific gravity of the unfoamed melt, casting said fluid foamed melt tofoam said shaped body, and cooling the cast melt to its solidificationpoint.

2. The method as in claim 1 wherein said inert gas is dispersed in saidmelt 'by blowing said gas into the melt while stirring.

3. The method as in claim 1 wherein air is dispersed in said melt byvigorously stirring said melt.

4. The method as in claim 1, wherein the inert gas is air.

5. The method as in claim 1, wherein the inert gas is carbon dioxide.

6. The method as in claim 1, wherein the inert gas is nitrogen.

7. The method as in claim 1 wherein said hydrophobing agent isstabilized with an acetoacetic ester.

8. The method as in claim 1 wherein said melt of hydrophobing agent isvigorously mixed with inert gas such that the specific gravity of theresulting solid foamed body is from 8050 percent of the specific gravityof the hydrophobing agent melted.

9. The method as in claim 1 wherein said melt of hydrophobing agent andinert gas are vigorously mixed with the melt at a temperature up to 4 C.above its dropping point.

10. The method as in claim 1 wherein shaped bodies particularly suitablefor convenient commercial use are prepared by casting said foamed meltinto a plurality of plastic-film bags contained within a carton.

References Cited by the Examiner UNITED STATES PATENTS 2,456,595 12/1948Rood 106-270 2,628,170 2/1953 Green 106270 2,892,732 6/1959 Rockland106-271 ALEXANDER H. BRODMERKEL, Primary Examiner.

D. I. ARNOLD, Assistant Examiner.

1. THE METHOD OF MAKING A SHAPED SOLID-FOAM BODY ADAPTABLE TO SOLUTIONOF ORGANIC SOLVENTS TO FORM TESTILE HYDROPHOBING SOLUTIONS, WHICH METHODCOMPRISES FORMING A MELT OF AN ANHYDROUS HYDROPHOBING AGENT CONSISTINGESSENTIALLY OF (A) 0.5 TO 3 PARTS BY WEIGHT OF PARAFFIN HAVINGSOLIDIFICATION POINT OF FROM 40* TO 100*C., (B) ONE PART OF WEIGHT OF AMEMBER SELECTED FROM THE GROUP CONSISTING OF (1) ALUMINUM, ZICONIUM, ANDTITANIUM ALCOHOLATES OF ALIPHATIC ALCOHOLS HAVING 2 TO 8 CARBON ATOMS,(2) SAID ALCOHOLATES RECTED WITH FROM 0.1 TO 3 MOLS OF A MONOCARBOXYLICALIPHATIC ACID PER MOL OF ALCOHOLATE, SAID ACID HAVING 1 TO 18 CARBONATOMS, AND (3) THE COMPOUNDS OF GROUPS (1) AND (2) REACTED WITH FROM 0.1TO 3 MOLS OF AN ALIPHATIC KETO-ENOL PER MOL OF COMPOUND, AND (C) 0.01 TO10 PERCENT, OF THE COMBINED WEIGHT OF (A) AND (B), OF AN ORGANIC SOLVENTSELECTED FROM THE GROUP CONSISTING OF LOWER ALIPHATIC ALCOHOL, TOLUENE,PERCHLOROETHYLENE, WHITE SPIRITS, AND MIXTURES THEREOF, DISPERSING ANINERT GAS IN SAID MELT IN AMOUNTS SUFFICIENT TO PRODUCE A FLUID FOAMEDMELT HAVING SPECIFIC GRAVITY ABOUT 95% TO 33% THAT THE SPECIFIC GRAVITYOF THE UNFOAMED MELT, CASTING SAID FLUID FOAMED MELT TO FOAM SAID SHAPEDBODY, AND COOLING THE CAST MELT TO ITS SOLIDIFICATION POINT.